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  • Effect of DED coating and D...
    Errico, V.; Fusco, A.; Campanelli, S.L.

    Surface & coatings technology, 01/2022, Letnik: 429
    Journal Article

    The advantages of the Laser Powder Bed Fusion process have led to growing interest from an industrial and academic point of view. However, the diffusion of this process has been slowed by technical challenges that have yet to be resolved, including non-optimal surface quality and low repeatability. To fix these issues and recover surface quality, several treatments are available. Our study focuses on one of them: the Directed Energy Deposition (DED) treatment, which in addition can be exploited for the repair of damaged components. In fact, the proposed study has been conducted by using AISI 316 L alloy both for producing parts throughout the L-PBF process and for coating them. Furthermore, a final Laser Scanning (LS) treatment has been carried out with the aim of maximizing the DED coating performances, in terms of surface roughness, microhardness and microstructural properties. To detect the anomalies that can emerge during the previous surface treatments, an optical monitoring system was implemented in the visible range by using a coaxial CCD camera, to monitor the geometry and morphology of the melt pool related to the DED and to the subsequent LS treatment. The results revealed many improvements in terms of surface roughness for the DED coating and even more for the LS treatment. Moreover, the latter was fundamental to improve the microhardness and the microstructural characteristics of the final coating. The data gathered and analyzed by the implemented monitoring system will allow making the treatment more stable and performing for future applications on complex geometries. •Coatings using DED + LS treatment on a L-PBF substrate were successfully achieved.•Laser scanning significantly improves DED coating performances.•Microstructure after the laser scanning treatment is an equiaxial fine grain.•The produced coating is uniform due to the stability of the melt pool.•Coatings quality was monitored in-process through optical and thermal systems.